https://kotlinlang.org logo
Channels
100daysofcode
100daysofkotlin
100daysofkotlin-2021
advent-of-code
aem
ai
alexa
algeria
algolialibraries
amsterdam
android
android-architecture
android-databinding
android-studio
androidgithubprojects
androidthings
androidx
androidx-xprocessing
anime
anko
announcements
apollo-kotlin
appintro
arabic
argentina
arkenv
arksemdevteam
armenia
arrow
arrow-contributors
arrow-meta
ass
atlanta
atm17
atrium
austin
australia
austria
awesome-kotlin
ballast
bangladesh
barcelona
bayarea
bazel
beepiz-libraries
belgium
benchmarks
berlin
big-data
books
boston
brazil
brikk
budapest
build
build-tools
bulgaria
bydgoszcz
cambodia
canada
carrat
carrat-dev
carrat-feed
chicago
chile
china
chucker
cincinnati-user-group
cli
clikt
cloudfoundry
cn
cobalt
code-coverage
codeforces
codemash-precompiler
codereview
codingame
codingconventions
coimbatore
collaborations
colombia
colorado
communities
competitive-programming
competitivecoding
compiler
compose
compose-android
compose-desktop
compose-hiring
compose-ios
compose-mp
compose-ui-showcase
compose-wear
compose-web
confetti
connect-audit-events
corda
cork
coroutines
couchbase
coursera
croatia
cryptography
cscenter-course-2016
cucumber-bdd
cyprus
czech
dagger
data2viz
databinding
datascience
dckotlin
debugging
decompose
decouple
denmark
deprecated
detekt
detekt-hint
dev-core
dfw
docs-revamped
dokka
domain-driven-design
doodle
dsl
dublin
dutch
eap
eclipse
ecuador
edinburgh
education
effective-kotlin
effectivekotlin
emacs
embedded-kotlin
estatik
event21-community-content
events
exposed
failgood
fb-internal-demo
feed
firebase
flow
fluid-libraries
forkhandles
forum
fosdem
fp-in-kotlin
framework-elide
freenode
french
fritz2
fuchsia
functional
funktionale
gamedev
ge-kotlin
general-advice
georgia
geospatial
german-lang
getting-started
github-workflows-kt
glance
godot-kotlin
google-io
gradle
graphic
graphkool
graphql
graphql-kotlin
graviton-browser
greece
grpc
gsoc
gui
hackathons
hacktoberfest
hamburg
hamkrest
helios
helsinki
hexagon
hibernate
hikari-cp
hire-me
hiring
hongkong
hoplite
http4k
hungary
hyderabad
image-processing
india
indonesia
inkremental
intellij
intellij-plugins
intellij-tricks
internships
introduce-yourself
io
ios
iran
israel
istanbulcoders
italian
jackson-kotlin
jadx
japanese
jasync-sql
java-to-kotlin-refactoring
javadevelopers
javafx
javalin
javascript
jdbi
jhipster-kotlin
jobsworldwide
jpa
jshdq
juul-libraries
jvm-ir-backend-feedback
jxadapter
k2-early-adopters
kaal
kafka
kakao
kalasim
kapt
karachi
karg
karlsruhe
kash_shell
kaskade
kbuild
kdbc
kgen-doc-tools
kgraphql
kinta
klaxon
klock
kloudformation
kmdc
kmm-español
kmongo
knbt
knote
koalaql
koans
kobalt
kobweb
kodein
kodex
kohesive
koin
koin-dev
komapper
kondor-json
kong
kontent
kontributors
korau
korean
korge
korim
korio
korlibs
korte
kotest
kotest-contributors
kotless
kotlick
kotlin-asia
kotlin-beam
kotlin-by-example
kotlin-csv
kotlin-data-storage
kotlin-foundation
kotlin-fuel
kotlin-in-action
kotlin-inject
kotlin-latam
kotlin-logging
kotlin-multiplatform-contest
kotlin-mumbai
kotlin-native
kotlin-pakistan
kotlin-plugin
kotlin-pune
kotlin-roadmap
kotlin-samples
kotlin-sap
kotlin-serbia
kotlin-spark
kotlin-szeged
kotlin-website
kotlinacademy
kotlinbot
kotlinconf
kotlindl
kotlinforbeginners
kotlingforbeginners
kotlinlondon
kotlinmad
kotlinprogrammers
kotlinsu
kotlintest
kotlintest-devs
kotlintlv
kotlinultimatechallenge
kotlinx-datetime
kotlinx-files
kotlinx-html
kotrix
kotson
kovenant
kprompt
kraph
krawler
kroto-plus
ksp
ktcc
ktfmt
ktlint
ktor
ktp
kubed
kug-leads
kug-torino
kvision
kweb
lambdaworld_cadiz
lanark
language-evolution
language-proposals
latvia
leakcanary
leedskotlinusergroup
lets-have-fun
libgdx
libkgd
library-development
lincheck
linkeddata
lithuania
london
losangeles
lottie
love
lychee
macedonia
machinelearningbawas
madrid
malaysia
mathematics
meetkotlin
memes
meta
metro-detroit
mexico
miami
micronaut
minnesota
minutest
mirror
mockk
moko
moldova
monsterpuzzle
montreal
moonbean
morocco
motionlayout
mpapt
mu
multiplatform
mumbai
munich
mvikotlin
mvrx
myndocs-oauth2-server
naming
navigation-architecture-component
nepal
new-mexico
new-zealand
newname
nigeria
nodejs
norway
npm-publish
nyc
oceania
ohio-kotlin-users
oldenburg
oolong
opensource
orbit-mvi
osgi
otpisani
package-search
pakistan
panamá
pattern-matching
pbandk
pdx
peru
philippines
phoenix
pinoy
pocketgitclient
polish
popkorn
portugal
practical-functional-programming
proguard
prozis-android-backup
pyhsikal
python
python-contributors
quasar
random
re
react
reaktive
realm
realworldkotlin
reductor
reduks
redux
redux-kotlin
refactoring-to-kotlin
reflect
refreshversions
reports
result
rethink
revolver
rhein-main
rocksdb
romania
room
rpi-pico
rsocket
russian
russian_feed
russian-kotlinasfirst
rx
rxjava
san-diego
science
scotland
scrcast
scrimage
script
scripting
seattle
serialization
server
sg-user-group
singapore
skia-wasm-interop-temp
skrape-it
slovak
snake
sofl-user-group
southafrica
spacemacs
spain
spanish
speaking
spek
spin
splitties
spotify-mobius
spring
spring-security
squarelibraries
stackoverflow
stacks
stayhungrystayfoolish
stdlib
stlouis
strife-discord-lib
strikt
students
stuttgart
sudan
swagger-gradle-codegen
swarm
sweden
swing
swiss-user-group
switzerland
talking-kotlin
tallinn
tampa
teamcity
tegal
tempe
tensorflow
terminal
test
testing
testtestest
texas
tgbotapi
thailand
tornadofx
touchlab-tools
training
tricity-kotlin-user-group
trójmiasto
truth
tunisia
turkey
turkiye
twitter-feed
uae
udacityindia
uk
ukrainian
uniflow
unkonf
uruguay
utah
uuid
vancouver
vankotlin
vertx
videos
vienna
vietnam
vim
vkug
vuejs
web-mpp
webassembly
webrtc
wimix_sentry
wwdc
zircon
Powered by
Title
z

zubzub

04/05/2017, 8:56 AM
sizeExtend & signExtend
o

olonho

04/05/2017, 9:06 AM
not sure if I understand, what's your point here. When casting 16-bit to 32-bit value, for example, there are diffrent ways of performing this operation for negative values, i.e. 0xffff can produce either 0x0000ffff (==65535 if seen as Int) or 0xfffffff (-1 if seen as Int), signExtend explicitly specifies that later behavior is taken
z

zubzub

04/05/2017, 9:11 AM
but how do you know when to extend and when to shrink?
o

olonho

04/05/2017, 9:20 AM
it depends on the API you're trying to call, look at generated bindings to see what type is in method signature
z

zubzub

04/05/2017, 9:22 AM
the size of the type is runtime dependend, so how do you know at compile time if you need to extend or shrink?
(or am I missing something?)
o

olonho

04/05/2017, 10:02 AM
Could you provide an example, so that we have better context?
z

zubzub

04/05/2017, 10:48 AM
say on one architecture size_t is 16-bit, on another architecture it's 64-bit
I have a 32-bit int that I need to convert to size_it
in one case I need to narrow it, in another case I need to extend it
how would I know which one to choose if the choice depends on the runtime?
o

olonho

04/05/2017, 11:25 AM
any really usable platform where this happens?
z

zubzub

04/05/2017, 11:40 AM
depends if you want to support something like arduino uno which is 16-bit
the thing is that the current approach only really works if you intend to compile code for 2 different sized architectures (eg 32 & 64)
(which is fine for me btw, it was mostly an observation)
one more question
does the extend or reduce call always reduce/extend size to the target type, or does it do it regardless of the target type's size?
*narrow
ie, if I call extend on a 32bit int, and my target size_t is 32bit at runtime, will it make it 64bit or keep it at 32bit?
o

olonho

04/05/2017, 2:21 PM
note that stubs are generated per-target, so
sizeof(size_t)
is known at compile time
s

svyatoslav.scherbina

04/05/2017, 2:29 PM
ie, if I call extend on a 32bit int, and my target size_t is 32bit at runtime, will it make it 64bit or keep it at 32bit?
These functions extend or reduce the size exactly to the target type. So if you call extend on a 32bit int, and your target size_t is 32bit, then it will keep it at 32bit.
say on one architecture size_t is 16-bit, on another architecture it's 64-bit
I have a 32-bit int that I need to convert to size_it
In this case you can convert your 32-bit
Int
to
Short
and then sign-extend it to
size_t
. It seems to be the most safe approach.
z

zubzub

04/06/2017, 12:59 PM
ok thanks, that makes things clear!